Internal conflicts take place within the main character's mind. When faced with a dilemma, for example, which choice should he/she make? Whatever the conflict is in the story, the main character will have to make some kind of decision or choice. Those are internal conflicts.
External conflicts take place between
**the main character and another character,
**the main character and something in nature (such as a storm or other natural occurrence), and/or
**the main character and some other force.
For example, one external conflict that both the husband and the wife struggle with in this story is their poor financial situation. Now ask yourself, what effect does this particular conflict have on the action in and outcome of the story?